Audio-visual signalling system for use in connection with stationary derricks, mobile cranes and the like during demolition and construction of buildings



June 21, 1966 F. m: PALMA @257,655

AUDIO-VISUAL SIGNALLING SYSTEM FOR USE IN COIIKIECTIOMv WITH STATIONARY DERRICKS, MOBILE CRANES AND THE LIKE DURING DEMOLITION AND CONSTRUCTION OF BUILDINGS Filed July ll, 1962 2 Sheets-Sheet 1 United States Patent Office Patented June 21, 1966 3,257,655 AUDIO-VISUAL SIGNALLING SYSTEM FOR USE IN CNNECTIUN WITH STATIONARY DERlRlCKS, MGBILE CRANES AND THE LIKE DURING DEM- ULITION AND CDNSTRUCTION F BUILDlNGS Frank De Palma, 436 Lincoln St., Palisades Park, NJ. Filed July 11, 1962, Ser. No. 209,081 7 Claims. (Cl. 340-286) This invention relates to yan audio-visual signalling system for use in connection with stationary derricks, mobile cranes and the like during the demolition and construction of buildings. More particularly, the invention pertains to a system of the character described for providing communication between a control man, that is to say, a man who is in a position able to watch an object (eg. a load) being moved, and an engineer who regulates the operation of the power source that actuates the derrick, crane or the like.

It is an object of the invention to provide a system of the character described that will enable a great variety of coded signals to be sent in both directions between the control man and the engineer, so that over and above the ability of the control man to communicate with the engineer solely for the regulation of vertical and horizontal motion of an object, the engineer can convey non-regulatory information to the control man and the control man can convey non-regulatory information to the engineer. Regulatory as used herein denotes information solely concerned with directing movement of the derrick, crane or the like. For example, it may be necessary for the control man to advise the engineer that the control man is leaving his station and this must be done without fear `that the engineer will confuse information of this character with instructions to move an object. Such confusion easily could result in a fatal or costly accident.

A system of the character described, which is utilized during erection or demolition of a building, obviously functions under hazardous conditions. otherwise moving object may sever the communication cable between the control man and the engineer, in which event communication would be broken off, or such an object could sever the line providing power to the system, in which event, likewise, communication would fail. In either case, if an object were being moved by the derrick or crane, great danger could result because this movement then would be without direction (without regulation by an observer). For instance, if an object were being lowered and communication were cut, the object might strike a passerby, a vehicle or a part of a building, since there would be no one to direct the operator in his manipulation of the power which actuates the crane or derrick.

If therefore is an object of the invention to provide `a system of the character described in which if the communication cable between the control man and the engineer is severed a warning signal automatically will be given to the engineer who thereupon forthwith should halt any object that is being moved by the derrick or crane.

It is another object of the invention to provide a system of the character described in which, in the event that the cable supplying power to the system from a utility power main is broken, a warning thereof will automatically be conveyed to the engineer and at the same time an auxiliary source of power cut in, such auxiliary source being in physical proximity to the engineer, so that there is no likelihood that it, too, will be disconnected.

It is another object of the invention to provide a system of the character described in which the control man is advised of the proper functioning of the system each time that he signals the engineer, whereby he is assured that the engineer is in receipt of his signal and therefore will A falling or properly handle the source of power that actuates the crane or derrick.

When operating a stationary derrick located on top of a -building the control man who is on the top lloor and who is known as the bell man cannot quickly and readily judge vertical locations of an object being moved by the derrick when the object is near the street level. It therefore is customary in such installations to have a second control man known `as a street man.

It is a further object of the present invention to provide a system of the character described wherein a provision is made, similar to the provision for the bell man, lto warn the engineer in the event that the communication cable -between the street man and the engineer accidentally is severed. This too will prevent serious accidents occurring at the street should an object through misdventure cut the street mans communication cable.

Other objects of the invention in part will be obvious and in part will be pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangements of parts which will be exemplified in the systems hereinafter described and of which the scope of applicati-on will be indicated in the appended claims.

In the accompanying drawings in which are shown various possible embodiments of the invention,

FIG. l is a circuit diagram of a signalling system embodying the present invention and used for providing communication between either the bell (high level control) man or the street (low level control) man, or both, and the engineer of a stationary derrick; and

FIG. 2 is a circuit diagram similar to FIG. l, but illustrating the invention as it is used to provide communication between a bell man and the engineer of a mobile crane.

As indicated previously, the high level control man whose post is at the upper level of a building at any given time (the actual level constantly changes during erection and demolition) is referred to in the trade as the bell man. The low level control man whose post is at the sidewalk level or thereabouts is referred to in the trade as the street man and the operator, whether he be the operator of the crane or the derrick, is referred to in the trade as the engineer.

The electric circuit diagram of FIG, l is of a type which is employed where a so-called stationary derrick is located on an upper story of a building, either the top story at any given time or one or two stories below the top story. Such a derrick is stationary in the sense that for a period of time, usually a few days or more, the derrick is located at one site, ordinarily about the middle of a oor, and it remains at this site until either continuing construction or continuing demolition necessitates raising or lowering of the derrick.

The derrick is operated as by means of heavy duty cables, i.e., long plural-stranded steel wires, which run to the derrick from multiple drums that are located .at a lower level, usually the ground floor or basement of the building. These drums and the clutches which operate them, as well as the motor which drives the clutches, ordinarily are vertically below the stationary derrick and therefore are at the middle of the ground floor or basement, The engineer, who is situated at the controls for the clutches and drums, is unable to see either `the derrick or the street, these being blocked from his view by the surrounding parts of the building. He therefore must rely entirely upon a communication system. A voice communication system is generally considered undesirable since it requires the engineer to wear earphones all day inasmuch as the engineer must at all times be instantly ready to engage or disengage the clutches for turning the drums. Accordingly, it is best to employ both a gongtype audio signal which the engineer usually will hear over the noise of construction or demolition and a visual signal such as a lamp which he can see and will attract his attention regardless of the noise. The combination of such a sound and light signal instantly and reliably will make the engineer aware of the operation that is required of him. In such an installation the bell man may not be able to judge accurately vertical heights at the street level and in such case there also is employed a street man. As soon will be seen, the within system provides cornmunication between the bell man and street man on the one hand and the engineer on `the other.

However the basic communication system by means of which either the bell man or the street man signals the engineer for the purpose of regulating the derrick is not in and of itself the basis of the presen-t invention. Rather the present invention concerns the enlargement, i.e. amplitication, of the basic signalling system in such a manner that additional circuit means are provided to supply further functions that make the overall signalling system far more useful.

One of the additional means is an electric circuit that will enable the bell man to signal the engineer so as to transmit a code message that is independent of a cornmunication for regulating the derrick; such a circuit can be used, -for example, if the bell man is about to leave his post and wishes to so advise the engineer.

Another additional means is an electric circuit that permits the engineer to transmit a code message to the bell man.

Still another additional means is an electric circuit that provides an ever present check to advise the bell man that his derrick regulatory communications are being received by the engineer so that the bell man can proceed to give such instructions with confidence.

Another additional means is an electric circuit that actuates an alarm for the engineer when the communication cable between the bell man and the engineer is broken so that the engineer can immediately stop the drums and prevent any accident from occurring.

Another additional means is an electric circui-t that renders effective an auxiliary source of power for the system should the cable from the power main be cut.

Another additional means is an electric circuit that actuates a signalling means which advises the engineer that the power cable has been cut and that he is operating on auxiliary power so that the break in the power cable can be repaired and the auxiliary power not unduly taxed.

Some of the foregoing additional circuit means likewise are included in connection with the communication system between the street man and the engineer. However as will be apparent, all such means need not be provided. For example, since the street man can readily and quickly approach the engineer in person i-t is not necessary to provide any auxiliary circuits for conveying non-regulatory messages between the street man and the engineer.

The circuit of FIG. l now will be described and from such description the elements that constitute the aforesaid various additional circuit means will become apparent. In FIG. l the reference numeral 10 denotes the bell mans communication equipment. The reference numeral 12 denotes the street mans communication equipment. The reference numeral 14 denotes the engineers communication equipment. The reference numeral 16 denotes the communication cable between the bell man and the engineer and the reference numeral 18 denotes the communication cable between the s-treet man and the engineer. These three units of communication equipment 10, 12 and 14 together with the two communication cables 16, 18 constitute the entire communication system 20.

The bell mans equipment 10 comprises a bell mans small light portable box (casing) which houses the electrical components and which has not been shown. Usually the bell man will wear this box on his chest where the controls are readily available to his lingers. The bell mans box has five push buttons 22, 24, 26, 28 and 30 which are accessible to the fingers of his hand. Conveniently two of these buttons 24, 26 are on the right hand side of the front face of the box, two buttons 28, 30 are on the left hand side of the front face of the box and the remaining button 22 is at the middle of the front face of the box. The right hand and left hand buttons are arranged one above the other so that the buttons 24 and 28 are respectively above the buttons 26 and 30.

Each of the buttons 22, 24, 26 and 30 controls a different momentary switch consisting of a pair of contacts. More particularly the button 22 controls a normally closed pair of switch contacts 32 and each button 24, 26, 28 and 30 controls a different normally open pair of switch contacts 34,36, 38 and 40, respectively. Also included in the bell mans equipment 10 and con-tained within the bell mans box is a signalling means such as a buzzer 42. The foregoing completes the bell mans equipment except for the wiring to lbe described.

It may be mentioned at this point that the right hand buttons 24, 26 are provided for the purpose of enabling the bell man to instruct the engineer as to the control of the drum that will move the load vertically (raise and lower). The left hand buttons 28, 30 are for the purpose of enabling the -bell men to instruct the engineer as to the control of the drum that will move the load horizontally (toward and away from the vertical axis of rotation of the derrick by varying the inclination of the boom). The purpose of the button 22 is to enable the bell man to communicate with the engineer for non-regulatory purposes, i.e. for purposes other than to instruct the engineer concerning horizontal and vertical movements of the load. The buzzer enables the engineer to communicate with the bell man, and also through its energization by suitable circuitry each time that any of the buttons 24, 26, 28 or 30 are pushed conrms to the bell man that the engineer has received his signal re-l garding the regulation of the load.

The street mans equipment 12 is basically the same as the bell mans equipment 10 except that it is less complex because the street man is on the ground and therefore does not need any additional non-regulatory communication means, usually does not need any means for instructing the engineer as to horizontal movement of the load and does not need any means for confirming to him that the engineer has received his (the street mans) Aload regulatory messages. Hence the street mans equipment which likewise may be housed in a small light portable box (not shown) only needs to constitute two push buttons 44, 46 -both of which are employed for the purpose of instructing the engineer concerning vertical movement of the load. Each button 44, 46 controls a different normally open pair of switch contacts 48, 50, respectively, of a momentary electric switch. As in the case of the bell mans equipment, the street mans equipment also includes wiring which soon will be described.

The bell mans communication cable 16 is a seven wire cable consisting of the wires 52, 54, 56, 58, 60, 62, and 64, respectively. The street mans communication cable 18 is a four wire cable consisting of the wires 68, 70, 72, and 74 respectively.

The engineers communication equipment 14 is more complex then the bell mans and street mans equipment because of more elaborate signalling means than the buzzer, Ibecause of the inclusion of relays (ampliliers) to overcome voltage drops in the communication cables 16, 18 and thereby insure positive operation of the signalling means, and because of an auxiliary power supply and means for sensing the failure of the main power cable and switching over to the auxiliary power Supply.

The engineers equipment 14 includes a main power section 75, an auxiliary power section 76, a means 78 5 for sensing failure of power from the main power section 75 and switching to the auxiliary power section, and relays, signalling means yand momentary and passive switches hereinafter detailed (a passive switch is one which will retain the condition in which it Ilast was placed).

At the bell mans equipment a common lead wire 80 is connected to the movable contact of each pair of contacts 32, 34, 36, 38 and 40 and to one terminal of the `buzzer 42. The said common lead wire 80 also is connected to the cable wire 52 in the lbell mans communication cable 16. The wire 54 runs from the cable 16 to the stationary contact of the pair of contacts 32. The wire 56 runs from the cable 16 to the stationary contact of the pair of contacts 34. The wire 58 runs from the cable 16 to the stationary contact of the pair of contacts 36. The wire 60 runs from the cable 16 to the stationary contact of the pair of contacts 38. The wire 62 runs from the Cable 16 to the stationary contact of the pair of contacts 40. The wire 64 runs from the cable 16 to the other terminal of the buzzer 42.

At the street mans equipment 12 a common lead Wire 82 is connected to the movable contact of each of the pair of switch contacts 48, 5t). The common lead wire 82 also is connected to both wires 68, 70 of the cable 18. The wire 72 of the cable 18 is connected to the stationary contact of the pair of contacts 48. The cable wire 74 is connected to the other contact of the pair of contacts 56.

The communication cables 16, 18 physically run from the locations of the lbell man and the street man, respectively, to the engineers communication equipment 14 where said cables are connected -to the engineers communication equipment by plugs and sockets 84, 86. lt is pointed out here that the plugs and sockets are so Wired that the wire 52 of the cable 16 is provided with a shunt lead wire 88 which is connected in parallel with said wire 52 when the plug 84 is inserted in its socket, and that the wire 68 of the cable 18 is provided with a shunt lead wire 90 which is placed in parallel with said wire 68 when the plug 86 is inserted in its socket.

The main power section 75 has a pair of power input lead wires 92, 94 that are connected to a nearby available A.C. power main outlet indicated :by the symbol 96. At least one power input lead wire includes a main control hand operated passive, eg. toggle, switch 98 and at least one power input lead wire, includes a fuse 100. The power input lead wires energize the primary winding 182 of a 12 volt step down transformer 104. Obviously 4any secondary voltage can be employed which is suitable to energize the various signalling means hereinafter to be described, 12 volts being mentioned merely by way of example. The secondary winding 166 of the transformer is connected to the input terminals 188 of a full wave rectifier bridge 110 having a filtering condenser 112 connected across the bridge output terminals 114. The positive and negative terminals have been indicated by appropriate plus and minus symbols in FIG. 1.

The auxiliary power section 76 simply constitutes a battery, e.g. a 12 volt storage battery, which has ample rreserve power to run the communication system for a fairly lengthy period of time, such as eight hours. The positive and negative terminals of the Ibattery likewise have been indicated by appropriate symbols.

The means 78 for sensing failure of power from the electric main 96 and for switching to the auxiliary power section 76 comprises a relay 116 having four movable contacts 118, 128, 122 and 124 all of which are operated concurrently upon energization of the coil of said relay. The movable contact 118 engages a stationary contact 126 when the relay 116 is idle and is swung against a stationary contact 128 when said relay is energized. The movable contact 120 is spaced from a stationary contact 136 when the relay 116 is idle and engages the contact when the'relay is energized. The movable contact 122 engages a stationary contact 132 when the relay 116 is idle and swings away to engage a stationary contact 134 when the relay is energized. The movable contact 124 engages a stationary contact 136 when the relay is idle and is swung away from this contact when the relay is energized.

A lead wire 138 runs from the negative output terminal of the rectifier -bridge to one terminal of the energization coil for the relay 116. A lead wire 140 runs from the positive output terminal of the rectifier bridge 110 to the other terminal of the energization coil for said relay 116. Thereby so long as the main switch 98 remains closed and the power input lead wires 92, 94 are unbroken, the relay 116 will be energized. Should the input Wires 92, 94 be severed or in any other way should power not be supplied from the bridge 110 the relay 116 will become idle (deenergized). Thereby this relay senses the failure of power from the electric main 96.

A lead wire 142 connects the lead wire 138 (at 12 volts negative potential) to the stationary contact 128. A lead wire 144 connects the lead wire 140 (at l2 volts positive potential) to the stationary contact 134. When the relay 116 is energized the movable contacts 118, 122 will respectively engage their stationary contacts 128, 134 so that at this time power from the rectifier bridge 110 and therefore from the power main 96 is vapplied to the communication system 21D.

A lead wire 146 runs from the negative terminal of the battery 76, optionally through a manually operated passive (eg. toggle) control switch 148 to the stationary contact 126. A lead wire 1511 runs from the positive terminal of the battery 76, preferably through `a fuse 152, to the stationary contact 132. Thus when the relay 116 is de-energized upon failure of power from the main 96 the movable contacts 118, 122 will be supplied with power from the auxiliary power section 76.

It is desirable to have some visual indication of which of the two power sections (main or auxiliary) is in operation at any given time and to this end the-re are provided a pair of power section indicating pilot lamps 154, 156. The D.C. pilot lamp 154 when lit indicates that the auxiliary power section 76 is in operation. To this end said pilot lamp 154 is connected by a lead wire 157 to the -movable Contact 124 and by a lead wire 158 to the negative terminal of the battery 76 on the far side of the switch 148. The stationary contact 136 is connected by a lead wire 159 to the lead wire 150 that runs to the positive terminal of the battery 76. Since the movable contact 124 engages the stationary contact 136 when the relay 116 is idle, at such time the pilot lamp 154 will be lit so as to show the engineer that the communication system is being operated by the auxiliary power section 76.

The A.C. pilot lamp 156 when lit indicates that the communication system 20 is being operated from the A.C. main 96. A lead wire 162 connects the pilot lamp 156 to the movable contact 120. Another lead wire 164 connects the pilot lamp to a lead wire that runs to the movable contact 122. When the relay 116 is energized positive potential is impressed upon the lead wire 160, this potential deriving from the rectifier bridge 110. Also at this time negative potential is applied to the contact 120 through the stationary contact `130 from the negative terminal of the rectifier bridge so that the pilot lamp 156 is lit.

Energization of the relay 116 opens the circuit for the D.C. pilot lamp 154 at the contacts 124, 136. Deenergization of the relay 116 opens the circuit for the A.C. pilot lamp 156 at the `contacts 120, 130. A lead wire 170 is connected to the contact 118. l

Since the lead wires 160 and 170v are respectively connected to the contacts 122 and 118 and since these contacts 122 and 118 have impressed thereon respectively positive and negative potentials from either the rectifier bridge 110 or the battery 76 at all times that the wmmunication system is operative (the control switches 98 and 148 being closed), said lead wires 160, 170 may be considered as the low voltage power buses for the communication system. To simplify reading of the circuit diagram I have used a heavy solid line for the positive bus 160 and a heavy dotted line for the negative bus 170, these heavy lines being branched throughout the circuit where ever positive or negative low voltage potential is supplied directly from the contacts 122 and 118. To avoid the presence of too many numbers on the drawings the reference numerals 160 and 170 have not been repetitiously employed.

The engineers communication equipment embraces, as indicated previously, various relays, signalling means and switches. These and the circuitry for connecting the same will now be described.

For controlling the vertical movement of the load the engineers communication equipment includes a vertical load relay 172 having four normally open pairs of contacts 174, 176, 178, 180. It may be mentioned at this point that the reason that the relay 172 is employed is, in effect, to act as an amplifier. It soon will be seen that signal voltages traverse the various communication cables in both directions and these may be quite lengthy so that the voltage drops therein can be appreciable. A voltage so reduced is sutiicient to actuate a relay (amplitier) but on occasion could fail to operate a signalling means, e.g. an audible signal, and it is to prevent such malfunctioning that the amplifier relay 172 is utilized. A horizontal load relay for the bell man and a vertical load relay for the street man, both of which relays and the circuitry associated therewith will be described hereinafter, are employed for the same purpose.

One terminal of the actuating coil of the Vertical load relay 172 is permanently connected to the positive low voltage bus 160. The other terminal of this actuating coil is connected by a lead wire 182 to the wire 56 of the communication cable 16. The negative low 'voltage bus 170 is connected to the Wire 88 so that when the plug and socket 84 are coupled negative potential appears on the common lead wire 80. Accordingly if the upper right audio-visual vertical load push button 24 is depressed to close the normally open pair of switch contacts 34 negative potential will appear on the lead wire 182 so as to energize the relay 172 and close all of its contacts.

Closu-re of the pair of contacts 176 brings negative potential from the negative low voltage bus 170 through the contacts 176 to a lead wire 184 that runs to one terminal of a gong or bell 186 the other terminal of which is permanently connected to the positive bus 160. This gong may be referred to as the vertical load gong and has a characteristic audible tone which may be imparted thereto in any one of various manners. Most conveniently this is accomplished by having said gong of a different size from another gong that will be described later. For example the gong 186 may be a ten inch single stroke gong. This means that the gong has a saucer-like vibrant metal disc about ten inches in diameter and a clapper which will strike. the disc once and then fall away from the disc each time that the audio-visual vertical load button 24 is pressed once and released. Attention is directed to the fact that the current applied to the gong for actuation of the same does not traverse the cornmunication cable 16 so that no appreciable loss in voltage is experienced.

The normally open pair of contacts 178 are connected in parallel with the normally open pair of contacts 176 so that energization of the vertical load relay 172 supplies two parallel paths for current to the gong 186. This is considered desirable since the relays are operating in a dusty atmosphere which could contaminate and thereby prevent operation of one of the pair of contacts. However it will be understood that the paralleling of the Contacts is not a critical feature of the invention.

Closure of the normally open pair of contacts 174 brings negative potential from the negative low voltage bus through the contacts 174 to a lead wire 188 that runs to one terminal of a vertical load lamp 190 which is associated with the vertical load gong 186. This association may be provided by having the lamp 190 physically disposed next to the gong 186 or by having it painted a characteristic color so that the engineer will know that the lamp 190 is a vertical load lamp. The other terminal of the lamp 190 is permanently connected to the positive bus 160. Thus when the audio-visual button 24 is pressed and released the gong 186 will sound once and the lamp 190 will light and then be extinguished.

Closure of the last normally open pair of contacts of the vertical load relay 172 places a positive potential on a lead wire 192 which runs to the cable wire 64 and thence to one terminal of t-he buzzer 42 the other terminal of which, it will be recalled, is connected to the negative bus 170 through the common lead wire 80, the cable wire 52 and the shunt lead wire 88.

rlhereby when the audio-visual vertical load push button 24 is depressed and released, three things will take place. iFirstly, the vertical load gong 186 will sound, secondly, the vertical load lamp will light and then become extinguished, and, thirdly, the buzzer 42 will sound for the period during which the push button is depressed. The sounding of the gong and the lighting of the lamp constitute a vertical load signal to the engineer. T-he sounding of the buzzer informs the bell man that the regulatory signal has been delivered to the engineer.

The description may be interrupted at this point to mention that by a proper coordinate manipulation of the vertical load gong 186 and the vertical load lamp 190 a set of coded signals, previously agreed upon between the control man and the engineer, is provided through the medium of which the bell man can definitely instruct the engineer as to the operation of the clutch that governs the drum which regulates vertical movement of the load. Purely by way of example the operation of the vertical gong 186 may instruct the engineer either to start or to stop the vertical load drum. The coded signals may be `as elaborate as required for any given job and as a matter of practice will be used in common throughout a large geographical area.

Pushing the visual vertical load push button 26 closes a circuit which only operates the verticalload lamp 190 but not the vertical load gong 1'86. More particularly, closing this push button 26 brings negative potential from the negative load bus 170 through the cable wire 52, the common lead wire 80, the closed contacts 36, the cable wire 58 and a lead wire 196 and the lead wire 188 to the lamp 190. A different coded signal may be provided for the lamp alone (visual signal solely). For instance this set of signals can indicate the speed at which the load wire to the derrick is moved whereas the combination of the gong and lamp (audio visual signal) may be used to instruct the engineer as to the direction of the movement of the vertical load wire.

A circuit which is essentially similar to the circuit just described for controlling movement of the vertical load wire is employed to control movement of the -horizontal load wire; movement of such wire under the control of the engineer causes the derrick lboom to vary its angle of inclination to the vertical.

More particularly, there is provided a horizontal load relay 198 having four normally open pairs of contacts 260, 202, 204, 206 corresponding to the contacts 174, 176, 178 and 189 of the vertical load relay 172. The contacts 202 and 204 are connected in parallel in the same fashion as the contacts 176 and 178 so that, in effeet, the horizontal load relay only has three normally open pairs of contacts.

The actuating coil for the horizontal load relay 198 has one terminal permanently connected to the positive bus 160. The other terminal of this actuating coil is connected by a lead wire 208 to the cable wire 60'of the communication cable 16 and then to the normally open pair of contacts 38 controlled by the audio-lvisual horizontal load push button 28 which is the upper left hand .push button. Hence when this push button is depressed it will bring negative potential from t-he common lead wire 80 to the actuating coil of the relay 198 to energize the same and close all of its normally open pairs of contacts.

Closure of the pairs of contacts 202 and 204 Will place negative potential upon a lead wire 212 running to one terminal of a horizontal load gong 214, the other terminal of which is permanently connected to the positive bus 160. The horizontal load gong 214 is so physically constructed as to emit a different sound from that of the vertical load gong 186. For example the construction of the gong 214 may be the same as that of the gong 186 but it may include a smaller vibrant metal disc, for instance one eight inc-hes in diameter. Like the gong 186, the gong 214 preferably is a single stroke gong so that it will sound but once for each closure and opening of the audio-visual horizontal load push button 28.

Closure of the pair of contacts 200 places negative potential on a lead wire 216 that runs to one terminal of a horizontal load lamp 218 the other terminal of which is permanently connected to the .positive bus 160; Accordingly the lamp 218 will be lit concurrently with energization of the horizontal load gong 214.

Closure of the pair of contacts 286 places positive potential on a lead wire 220 which runs to the lead wire 192 and hence sounds the buzzer 42.

It now will be appreciated that depressing the audiovisual horizontal load push button 28 and releasing it sounds the horizontal load gong 214, lights and then eX- tinguishes the horizontal load lamp 218 and, for the period of time that the push button is depressed, energizes the buzzer 42.

Closure of the lower left hand visual horizontal load push button 38 places negative potential on the cable wire 62 that is connected to a terminal of the horizontal load lamp 218 so that this lamp can be flashed independently of the ringing of the horizontal load gong 214.

From t-he foregoing it now will be apparent that by proper manipulation of the upper right hand (audio-visual) and lower right hand (visual) vertical load push buttons 24, 26 and of the upper (audio-visual) and lower (visual) left hand horizontal load push buttons 28, 30, the engineer through the'medium of the gongs 186 and 214 and the lamps 190 and 2118 can con-Vey regulatory information through a preagreed code of signals to the engineer, `this -code being of suicient elaborateness, through the ability to operate each gong and its corresponding lamp concurrently through closure of an upper push button, or the lamp alone through closure of the lower push button.

It will, of course, be understood that the aforesaid gongs and lamps are in the immediate physical vicinity of the engineer, being so close that he must hear the sound and being so positioned that he must see the lights if he is reasonably alert.

As pointed out previously the system includes suitable means for giving an alarm to the engineer if either communication cable should fail.4 Said alarm circuit includes a communication fai-lure (continuity) relay 224 having a pair of normally closed contacts 226, 228. The actuating coil of the continuity relay 224 has one terminal permanently connected to t-he positive bus 160. The other terminal is connected by a lead wire 230` to the cable wire 54 which runs to the normally closed pair of contacts 32. Said contacts are connected by the common lead wire `80 to the cable wire 52 and thence to t-he negative bus 170. Thereby as long as the pair of contacts 32 remains closed (the nonregulatory push button 22 is not depressed) and the cable 1-6 is intact the relay 224 will remain energized and will hold its contacts 226, 228 open.

1f the communication cable is severed negative potential will be removed from the lead wire 230 to deenergize the relay 224 and permit its contacts 226, 228 to close.

One contact of each of said pair of contacts 226, 228 is connected to the negative bus 170 through the shunt lead `wire `88 which runs into the lead wire 236 that exl tends to the contacts 226, 228. The other contacts of the pairs of contacts 226, 228 are connected in parallel to a lead wire 238, the two parallel pairs of contacts 226, 228 being employed to make certain that at least one of them will operate when the relay 224 is deenergized.

The lead wire 238 has two branches 240, 242. One branch 248 runs through a passive contact switch 241 t0 a continuity failure gong 244. The other -branch 242 runs to a continuity failure l-amp 246. One terminal of each of the continuity failure lamp and the continuity failure gong is permanently connected to the positive lead bus 160. It will be apparent that when the continuity relay 224 deenergizes upon severing of the communication cable 16 potential will be applied to the continuity failure gong and the continuity failure lamp. Both of these are in the immediate physical vicinity of the engineer and are so located that he must see and hear them if he is at his post. The gong 244 is of the multiple repeating type, e.g. it includes a make and break relay in its internal circuit, so that it continues to sound by repeated strokes. It has a tone which is distinctly different from those of the other gongs. As soon as the engineer hears this gong 244 sound continually and he sees the lamp 246 light continuously he stops both load drums so that wherever the load may be it will not be moved any further, either horizontally or vertically and operations will be suspended until the communication system 20 can be re-established. Attention is called to the presence of a fuse 247 in the positive lead bus 160 beyond the point of connection to the failure gong and lamp. This arrangement assures application of power to said gong and lamp in the event a short circuit develops in the communication system, as

by crossing wires when a communication cable is accidentally cut, and the short circuit blows said fuse. The fuse 247 is of lower capacity than the other fuses in order to protect the failure alarms.

It will be recalled that the present invention also provides a circuit means for enabling the bell man to send a non-regulatory communication to the engineer, i.e., la cornmunication which does not effect the horizontal or vertical movement of the load. Such circuit means conveniently comprises in part the same circuit means that activates an alarm in the event that the cable 16 is severed. In other words, the bell mian-to-engineer non-regulatory communication means includes the same circuit as the continuity circuit `(the circuit which raises an alarm upon failure of the communications caused by breaking of the communication cable 16).

More specifically, the last named non-regulatory cornrnunication circuit is rendered effective for communication purposes from the bell man to the engineer oy the inclusion of the pair of normally closed contacts 32. It will have been observed by an understanding reader that the normally closed pair of contacts 32 were not necessary for the continuity circuit; however, by virtue of their presence and that of the non-regulatory communication push button 22 which enables these normally closed contacts to be opened momentarily if desired the aforesaid non-regulatory communication is created.

If the bell man wishes to send a message to the engineer which is nonregulatory-in nature he depresses the push button 22 according to a prearranged certain code. Each time the push button 22 is depressed the continuity failure gong 244 will be sounded and the continuity failure lamp 246 will be lit. The enginer will be aware since said gong and light are not continuously energized as they are in the event of a cable discontinuity that a message is being transmitted to him according to a prearranged code.

Mention heretofore has been made of warning the engineer when the power lead lines 92, 94 are broken. This warning of course simply is energization of the DC. lamp 154 in the manner previously described.

The signalling system further includes a circuit for enabling the engineer to communicate with the bell man. Up to this point it will be appreciated that with the system as described the bell man can send both regulatory and non-regulatory messages to the engineer and the bell man is advised via the buzzer 42 of the receipt of the regulatory messages from the engineer, but there has not yet been described a circuit for enabling the engineer to communicate with the -bell man. This latter circuit employs the buzzer 42 and a pair of momentary switches with normally open pairs of contacts 248, 250. The pairs of contacts 248, 250 are connected in parallel so that closure of either of them has the same efect. Two such pairs of contacts are employed to enable them to be physically disposed in different locations. For instance, one of the pair of contacts may be located immediately adjacent the engineer where he can close them without leaving his post.- Another such pair of contacts can be located near the junction 'box where all the connections are made.

One contact of each pair of contacts 243, 250 is permanently connected to the positive lead bus 160. Both other contacts are connected to the lead wire 192 that runs via the cable wire 64 to one terminal of the buzzer 42 the other terminal of which, as has been pointed out previously, is connected through the cable wire 52 to the negative bus 170. Thus, closure of either one of the normally open pair of contacts 248, 250 will sound the buzzer 42. The bell man can distinguish between a message from the engineer and a confirmation of the bell mans signal to the engineer because he will hear the buzzer 42 sound 'at times other than when he depresses one of the push buttons 24 or 28. Obviously a prearranged code is provided for communication via the buzzer 42 from the engineer to the bell man.

A generally similar set of circuits but of less sophisticated form is provided for the street man. These include a vertical load relay 252 and a continuity relay 254 similar to the vertical load relay 172 and the continuity relay 224 for the bell man. The street mans circuit is not shown with a horizontal load relay since ordinarily this is not needed. Of course, such a relay can be employed if it is necessary or desirable in any given circumstance. Furthermore, the street mans circuit usually will not include means for communication between the street man and engineer, or vice versa, since it is relatively easy for the street man to walk over to the engineer.

One terminal of the actuating coil for the street mans vertical load relay 252 is permanently connected to the positive bus 160. The other terminal of .this actuating coil is connected by a lead wire 256 and the cable wire 72 of the communication cable 18 to one of the contacts of the normally open pair of contacts 48. The other of said contacts is connected via the common lead wire 82 and the cable wire 68 of the communication cable 18 to the negative bus 170. Hence ,as soon as the audiovisual vertical load push button 44 is closed the relay 252 will be actuated. The relay 252 has three normally open pairs of contacts 262, 264 and 266. The pairs of contacts 264 and 266 are connected in shunt so that operation of at least one of them will be assured.

Closure of either or both of the lpairs of contacts 264, 266 connects the negative bus 170 to a lead wire 268 that runs to one terminal of the vertical load gong 186 the other terminal of which is permanently connected to the positive load bus 160. Therefore depression of the audio-visual vertical load push button 44 will sound the vertical load gong.

Closure of the pair of contacts 262 brings negative potential from the negative bus 170 to a lead wire 270 that runs to one terminal of a properly identiiied (eg. by a special color) street mans vertical load lamp 272.

Hence depression of the audio-visual vertical load push button 44 in addition to sounding the vertical gong 186 that is common to the bell man and the street man also will light up the street mans vertical load lamp 272 so that the engineer knows who is giving the vertical load signal. The street mans vertical load lamp is located near the other load lamps 190, 218 so that illumination thereof cannot be overlooked by the engineer. Depression of the visual vertical load push button 46 will close the Vcontacts 50 to bring negative potential via the cable wire 74 and a lead wire 276 to the street mans vertical load lamp. Thus, like the bell man, the street man can operate his vertical load lamp independently of the vertical load gong so that by means of the same code that the bell man uses the street man can send regulatory communications (concerning vertical manipulation of the load) to the engineer.

If desired, a buzzer similar to the buzzer 42 may be incorporated in the street mans communication equipment 12 so that the street man may know that the engineer has received his regulatory communication.

One terminal of the continuity relay 254 is permanently connected to the positive bus 160. The other terminal of this relay is connected through a lead wire 278 to the cable wire 70 and thence to the common lead wire 82. From the common lead wire 82 this circuit runs through the -cable wire 68 to the shunt lead wire 90 that is connected to the negative bus 170. Therefore so long as the street mans cable 18 is unbroken the continuity relay 254 will remain energized. No pair of normally closed contacts located in the street mans communication equipment is included in the foregoing circuit because as just pointed out such wire communication ordinarily is not necessary.

Should the cable 18 fail, power to the actuating coil of the continuity relay 254 is cut oft'. Said relay 254 has twin shunt connected pairs of normally closed contacts 282, 284, the same being connected in parallel as a precaution against contact fouling as mentioned earlier. When the relay 254 deenergizes negative potential is applied from the negative bus 170 through the shunt lead wire and the lead wire 286 through said contacts to a lead wire 288 which runs to the lead wire 288, whereby deenergization of the street mans continuity relay 254 will energize the continuity failure gong 244 and light the continuity failure lamp 246 in indicate a communication cable break. The engineer thereupon will stop movement of the load.

FIG. 2 shows a 'signalling system which is very similar to the signalling system shown in FIG. l. Essentially it differs therefrom in that there is only one control man, to wit, a bell man, because this system is intended to be used with a mobile crane. In such case the engineer sits outside the building to ybe erected or demolished, in the control cab of the crane, and thereby is, in etect, his own street man. Therefore no street man signalling equipment is necessary. This enables an additional sophistication to be added to the bell mans circuit without utilizing any extra wires in the bell mans cable.

With a stationary derrick it is apparent that the boom must be turned in azimuth. Quite usually this is done with manpower and therefore it is not necessary to signal the engineer since the men who turn the boom in azimuth are located on the then top floor of the building. But where a mobile crane is employed, the azimuth position of the boom must be regulated by the engineer at the street level rather than by men in the vicinity of the bell man. Hence 4it is desirable where a mobile crane is being used, for the signalling system to include a circuit that enables the bell man to send a regulatory message relating to the azimuth movement of the boom as well as vertical and horizontal movement of the load. Such a signalling system can be provided with a bell mans communication equipment and with a bell mans :communication cable that are identical to the bell mans communi- 13 cation equipment and cable 10, 14, described withrespect to FIG. 1.

Referring in detail to FIG. 2 the bell man is provided with communication equipment 290 .and the engineer with communication equipment 292. These two pieces of equipment are connected by a communicatron cable 294.

The bell mans communication equipment comprises a bell mans box which he conveniently will wear on his chest. The box has five push buttons 296, 298, 300, 302 an-d 304. The push button 29S is at the upper right hand side of the front wall of the bell mans box, the push button 300 at the lower right hand side of said wall, the push button 302 is at the upper left hand side of said wall and the push button 304 is at the lower right hand side of the wall. The push button 296 is located in the middle of the wall.

The push button 296 controls a normally closed momentary switch having a normally closed pair of contacts 306. Each of the push buttons 298, 300, 302 and 304 controls a different momentary switch having, respectively, normally open pairs of contacts 303, 310, 312 and 314.

The movable contact of each of the pairs of contacts is connecte-d to a common lead wire 316. The communication cable 294 is a seven wire cable having the cable wires 318, 320, 322, 324, 326, 328 .and 330. The cable wire 318 is connected to the common lead wire 316. The cable wires 320, 322, 324, 326 `and 328 are connected, respectively, to the stationary contacts of the pairs of contacts 306, 308, 310, 312 and 314. The cable wire 330 is connected to one terminal of a buzzer 332 the other terminal of which is connected to the common lead wire 316.

The signalling system of FIG. 2 is powered by a battery 334 although, if desired, an alternate connection may be provided to an A.C.'source of power. Because the crane is mobile it quite often will suffice -to totally power the system only from such a battery, or a generator on the crane, thereby to render the system independent of a local power sourcel The negative terminal of the battery is connected to a negative bus 336 optionally through a manually controlled passive (toggle) switch 338 or the like while the positive terminal of the battery is connected to a positive bus 340 optionally including fuses 342, 344. As in the case of FlG. l the negative bus has been indicated by a heavy dotted line and the positive bus by a heavy solid line. Both of these buses branch throughout FIG. 2 and are unencumbered by multiple repetitions of the aforesaid reference numerals.

The engineers communication equipment includes a vertical load relay 346, a horizontal load relay 348, a boom azimuth relay 350 and a continuity relay 352.

The vertical load relay 346 has four normally open pairs of contacts. Since these contacts are the same in function as the contacts of the vertical load relay 172, said contacts of the relay 346 and'their circuitry will not be described in great detail.

One terminal of the actuating coil for the relay 346 is permanently connected to the positive bus 340. The other terminal of said actuating coil is connected by a lead line and the cable wire 322 to the normally open pair of contacts 308 so that when the audio-visual vertical load push button 29S is depressed the vertical load relay 246 will be energized.

Energization of the vertical load relay 346 closes twin parallel connected pairs of contacts which bring negative potential from the negative bus 336 to a lead wire 354 that is connected to one terminal of a single stroke vertical load gong 356 the other terminal of which is permanently connected to the positive bus 340. Another pair of normally open contacts of the vertical load relay 346 is connected by a lead wire to one terminal of a vertical load lamp 35S the other terminal of which is permanently connected to the positive bus 340. Hence depression and subsequent release of the audio-visual vertical load push button 298 will sound the ver-tical load gong 356 and will energize and then deenergize the vertical load lamp 358. Both this gong and its associated lamp are in the physical Vicinity of the engineer of the mobile crane so that he will hear and see the same. The fourth pair of normally open contacts of the vertical load relay 346 upon closure will place positive potential on a lead wire 360 that runs Via the cable wire 330 to one terminal of the buzzer 332 the other terminal of which is permanently connected through the cable wire 318 to the nega-tive bus 336.

To summarize, when the audio-visual vertical load push button 298 is depressed and then releaesd it will sound its associated gong, temporarily light its associated lamp and sound the buzzer 332 in the bell mans box, the latter being a confirmation to the bell man that the engineer has received the regulatory communication concerning vertical movement of the load.

Depression of the visual vertical load push button 300 will place negative potential on a terminal of the vertical load lamp 358 independently of the energization of the actuating coil of the vertical load relay whereby this lamp thereby can be lit by the bell man without sounding the gong 356. Such arrangement permits delicate control of speed during accent or descent of the load.

Depression of the audio-visual horizontal load push button 302 energizes the actuating coil of the horizontal load relay 348 which has four normally open pairs of contacts. Two pairs of these contacts, connected in parallel, upon closure lead negative potential from the negative bus 336 to a lead wire 362 running to one terminal of a horizontal load gong 364 which is of the single stroke variety and has a tone different from that of the vertical load gong 356. Closure of the third normally open pair of contacts of the horizontal load relay 348 brings negative potential to a horizontal load lamp 366 the other terminal of which is permanently connected to the positive bus 340. The fourth pair of open contacts of the open relay 348 upon closure leads positive potential to the lead wire 360 with consequent energization of the buzzer 332. Thereby each time that the audio-visual horizontal load push button 302 is depressed and released the horizontal load gong will sound, the horizontal load lamp will energize and then extinguish and the buzzer 332 will ring for the period of time that the push button is depressed. The communication system has been found to operate satisfactorily without a separate bell mans visual horizontal load button for lighting the horizontal load lamp 366 independently of operation of the horizontal load gong 364.

Depression of the push button 304 will energize the actuating coil of the boom azimuth relay 350. This latter relay has two pairs of normally open contacts in parallel which upon closure when the relay is energized will place negative potential from the negative bus 336 on a lead wire 368 connected to one terminal of a boom azimuth gong 370 of the single stroke type and of a distinctly different tone. A third pair of normally open contacts of the relay 350 will upon energization of said relay apply negative potential to one terminal of a boorn azimuth lamp 372 the other terminal of which is permanently connected to the positive bus 340. The fourth normally open pair of contacts of the relay 350 upon closure will place positive potential on the lead wire 360 to energize the buzzer 332. Thus depression of the audio-visual boom azimuth push button 304 followed by its release will sound the single stroke boom azimuth gong 370, energize and then deenergize the boom azimuth lamp 372 and ring the buzzer 332 for as long as the push button is depressed. As in the case of the horizontal load regulatory signals it has been found that it is satisfactory to operate the boom azimuth control without a separate regulatory signal for the boom azimuth lamp 372 by itself.

To enable the engineer to Communicate with the bell man the engineers equipment 292 includes a pair of normally open manually op'erable momentary switches 374, 376 connected in parallel. Two such switches are used to enable them to be located in physically different sites. For instance, one switch may be inside the engineers cab on the mobile crane an-d the other switch may be near the building. A lead wire 37S connects one side of each switch to the lead wire 360. The other side of each switch is permanently connected to the positive bus 340. Hence closing either one of these switches actuates the buzzer 332. A suitable code is agreed upon for such signals transmitted from the engineer to the control man.

One terminal of the actuating coil of the continuity relay 352 is permanently connected to the positive bus 340. The other terminal of this coil is connected through lead wires `and the cable wire 320 to the normally closed contacts 306 in the bell mans equipment and then through the common lead wire 316 and communication cable wire 318 to the negative bus 336 whereby as long as `the communication cable 294 is intact and the push button 296 is idle the relay 352 is actuated. Obviously severing of the communication cable will deenergize the continuity relay.

The continuity relay has twin normally closed parallel connected pairs of contacts 382, 384 that are connected at the cable plug and socket 347 to the negative bus 336. When the continuity relay is deenergized the consequent closure of either or both of these contacts places negative potential on lead wires running to one terminal of a repeating stroke continuity alarm gong 338 and one terminal of a continuity alarm lamp 390. The other terminals of the gong and lamp are permanently connected to the positive bus 340. Thus deenergization of the continuity relay upon severing of the communication cable 294 will cause the continuity alarm gong to ring and will illuminate the continuity alarm lamp.

For the bell man to transmit nonregulatory communications to the engineer the bell man simply depresses the push button 296 in accordance with an agreed upon code. This will energize the signalling means constituting the continuity alarm gong 388 and lamp 390 pursuant to said code. The engineer can distingush between such a nonregulatory communication and a continuity failure alarm by virtue of the fact that the alarm is continuous whereas the nonregulatory communication code will constitute bursts of energization.

To inform the engineer that the signalling system is in operation an operation lamp 392 is connected by lead wires between the two buses 336, 340, the connection however being beyond the main control switch 33S.

It thus will be seen that there have been provided systems which achieve the several objects of the invention and which are well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention, made in the embodiments set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described the invention, there is claimed as new, and is desired to be secured by Letters Patent:

1. In a signalling system for communiaction between a control man and an engineer for regulating the operation of a stationary derrick, a mobile crane or the like and in which system equipment for a control man is connected to equipment for an engineer by a communication cable, the control mans equipment including plural manually operable switches and the engineers equipment including a source of power, plural signalling means land circuits for selectively energizing the various signalling means from the source of power upon selective operation of the switches: the combination therewith of a further signalling means in the engineers equipment, a lirst circuit means in the engineers equipment for operatand as various changes might be' ing said further signalling means from the source of power, a switch in said first circuit means, a second circuit means running through the communication cable for operating said last-named switch, said second circuit means holding said last-named switch open when the communication cable is intact and closing the switch in the first circuit means when the communication cable is severed whereby upon severance of said cable the further signalling means will be energized in a continuous fashion, and a further manually operable switch at the control mans equipment, said last-named switch being series connected in the second circuit means whereby intermittent operation of said further switch by the control man will transmit a nonreg'ulatory communication to the engineer by intermittent operation of the further signalling means at the engineers equipment.

2. In a signalling system for communication between a control man and an engineer for regulating the operation of a stationary derrick, a mobile crane or the like and in which system equipment for a control man is connected to equipment for an engineer by a communication cable, the control mans equipment including plural manually operable switches and the engineers equipment including a source of power, plural signalling means and circuits for selectively energizing the various signalling means from the source of power upon selective operation of the switches: the combination therewith of a first further signalling means in the engineers equipment, a rst circuit means in the engineers equipment for operating said further signalling means from the source of power, a switch in said first circuit means, a second circuit means running through the communication cable for operating said last-named switch, said second circuit means holding said last-named switch open when the communication cable is intact and closing the switch in the first circuit means when the communication cable is severed whereby upon severance of said cable the further signalling means will be energized in a continuous fashion, a second further signallying means in the control mans equipment, and circuit means running through the communication cable for energizing said second further signalling means from the source of power at the engineers equipment upon operation of the manually operable switches in the control mans equipment.

3. In a signalling system for communication between a control man and an engineer for regulating the operation of a stationary derrick, a mobile crane or the like and in which system equipment for a control man is connected to equipment for an engineer by a communication cable, the control mans equipment including plural manually operable switches and the engineers equipment including a source of power, plural signalling means and circuits for selctively energizing the various signalling means from the source of power upon selective operation of the switches: the combination therewith of a further signalling means in the control mans equipment, circuit means running through the communication cable for energizing said further signalling means from the source of power at the engineers equipment upon the operation of the manually operable switches in the cont-rol mans equipment, a manually operable switch in the engineers equipment, and circuit means for operating the further signalling means from the source of power upon operation of the manually operable switch in the engineers equipment.

4. In a signalling system for communication between a control man and an engineer for regulating the operation of a stationary derrick, a mobile crane or the like and in which system equipment for a control man is connected to equipment for an engineer by a communica- Ition cable, the control mans equipment including plural manually operable switches and the engineers equipment including a source of power, plural signalling means and circuit for selectively energizing the various signalling means from the source of power upon selective operation of the switches: the combin-ation therewith of a further signalling means in the engineers equipment, a iirst circuit means for operating said further signalling means from the source of power, a switch in said rst circuit means, and a second circuit means running through the communication cable for operating the last-named switch, said second circuit means holding the last-named switch open when the communication cable is intact and closing the switch in the first circuit means when the communication cable is severed whereby upon severance of said cable the further signalling means in the engineers equipment will be energized in a continuous fashion.

5. A signalling system for communication between two control men and an engineer for regulating a stationary derrick, a mobile crane or the like, said system including a iirst control mans equipment, a second control mans equipment, an engineers equipment, a rst communication-cable connecting the rst control mans equipment to the engineers equipment, a second communication cable connecting the second control mans equipment to the enginers equipment, a manually operable switch in the first control mans equipment, a manually operable switch in the second control mans equipmnt, signalling means in the engineers equipment, a source of power in the engineers equipment, circuit means including both communication cables for energizing the signalling means from the source of power upon operation of the switch at either control mans equipment, a first further signalling means in the engineers equipment, a second further signalling means in the engineers equipment, circuit means for energizing one or the other of the two further signalling means from the source of power upon operation of, the respective switch so that the engineer can ascertain which control man is energizing the first-named signalling means, a third further signalling means in the engineers equipment and means responsive to the severance of either communication cable for energizing the third further signalling means.

6. A signalling system as set forth in claim 5 wherein the equipment of at least one of the control men includes a signalling means, wherein the control mans equipment with the signalling means includes an additional manually operable switch for actuating the third signalling means and wherein circuit means is provided for energizing the signalling means in said control mans equipment from the source of power upon energization of the signalling means in the engineers equipment.

7. A signalling system for communication between a control man and an engineer for regulating a stationary dei-rick, a mobile crane or the like, said system including a control mans equipment, an engineers equipment and a communication cable connecting said equipment, said control mans equipment including a first manually operable vertical load switch, a second manually operable vertical load switch, a manually operable horizontal load switch, a manually operable nonregulatory communication switch and a signalling means, said engineers equipment including a vertical load relay, a rst vertical load signalling means, a second vertical load signalling means, a horizontal load relay, a horizontal load signalling means, a continuity relay, a continuity signalling means, a manually operable switch and a source of power, rst circuit means for energizing the vertical load relay from the source of power upon actuation of the iirst vertical load switch, second circuit means for energizing both vertical load signalling means from the source of power upon energization of the vertical load relay, third circuit means for energizing the second vertical load signalling means from the source of power upon actuation of the second vertical load switch, fourth circuit means for energizing the horizontal load relay from the source of power upon actuation of the horizontal load switch, fth circuit means for energizing the horizontal load signaling means from the source of power upon energization of `the horizontal load relay, sixth circuit means for energizing the signalling means at the control mans equipment upon energization of either the vertical load relay or the horizontal load relay, seventh circuit means running through the communication cable for energizing the continuity relay from the source of power, said seventh circuit means including the manually operable nonregulatory connection switch, eighth circuit means operable when the continuity relay is deenergized for actuating the continuity signalling means from the source of power, and ninth circuit means for energizing the signalling means at the control mans equipment upon actuation of the switch at the engineers equipment, said first, third, fourth, sixth, seventh and ninth circuit means including the communication cable.

References Cited by the Examiner UNITED STATES PATENTS 935,320 9/1909V Nye 340-286 1,194,458 8/1916 Yates 340-286 1,559,312 10/1925 Cadieux 340-286 1,575,599 3/ 1926 Hornberger.

2,736,012 2/1956 Bland et al 340-333 X FOREIGN PATENTS 417,030 9/ 1934 Great Britain.

NEIL C. READ, Primary Examiner.

A. I. KASPER, Assistant Examiner. 

3. IN A SIGNALLING SYSTEM FOR COMMUNICATION BETWEEN A CONTROL MAN AND AN ENGINEER FOR REGULATING THE OPERATION OF A STATIONARY DERRICK, A MOBILE CRANE OR THE LIKE AND IN WHICH SYSTEM EQUIPMENT FOR A CONTROL MAN IS CONNECTED TO EQUIPMENT FOR AN EENGINEER BY A COMMUNICATION CABLE, THE CONTROL MAN''S EQUIPMENT INCLUDING PLURAL MANUALLY OPERABLE SWITCHES AND THE ENGINEER''S EQUIPMENT INCLUDING A SOURCE OF POWER, PLURAL SIGNALLING MEANS, AND CIRCUITS FOR SELECTIVELY ENERGIZING THE VARIOUS SIGNALLING MEANS FROM THE SOURCE OF POWER UPON SELECTIVE OPERATION OF THE SWITCHES: THE COMBINATION THEREWITH OF A FURTHER SIGNALLING MEANS IN THE CONTROL MAN''S EQUIPMENT, CIRCUIT MEANS RUNNING THROUGH THE COMMUNICATION CABLE FOR ENERGIZING SAID FURTHER SIGNALLING MEANS FROM THE SOURCE OF POWER AT THE ENGINEER''S EQUIPMENT UPON THE OPERATION OF THE MANUALLY OPERABLE SWITCHES IN THE CONTROL MAN''S EQUIPMENT, A MANUALLY OPERABLE SWITCH IN THE ENGINEER''S EQUIPMENT, AND CIRCUIT MEANS FOR OPERATING THE FURTHER SIGNALLING MEANS FROM THE SOURCE OF POWER UPON OPERATION OF THE MANUALLY OPERABLE SWITCH IN THE ENGINEER''S EQUIPMENT. 